EP0433105A1 - Catalyst support for olefinic polymerization, process for preparing the same and catalyst obtained therefrom - Google Patents

Abstract

Catalyst support in the form of solid particles consisting essentially of a complex of MgCl2 and of alcohol, characterised in that the complex of formula MgCl2.x(n-BuOH) in which 0.1 </= x </= 2, has a specific surface of 1 to 20 m<2>/g, the porosity of the particles being from 1 to 2 cm<3>/g. <??>The support is obtained from an emulsion of a solution of MgCl2 in an excess of n-butanol from which the complex is precipitated by a compound SiClxR4-x with 1 < x < 4 and R being a saturated hydrocarbon radical containing from 1 to 4 carbon atoms, the complex formed being in the emulsion and during the precipitation at a temperature not exceeding 50 DEG C. <??>The support is employed in the catalyst components for olefin polymerisation or copolymerisation.

Description

The present invention relates to a catalyst support essentially consisting of a complex of magnesium chloride and n-butanol (n-BuOH). This complex formed of particles of high pore volume has a low specific surface. It is prepared by precipitation of MgCl₂ in solution in n-butanol, at a temperature below the melting point of the complex, from an emulsion of said solution.

A catalyst for the polymerization of olefins can be obtained from the support by deposition under known conditions of a transition metal compound as well as any other components usual for this type of catalyst.

According to GB-A 2 029 840 it is known to mix a magnesium chloride, an alcohol or a phenol and a mineral oil and to form an emulsion of the whole at a temperature of approximately 120 ° C. in order to maintain the molten magnesium chloride-alcohol or phenol complex. After quenching the hot emulsion in a very cold non-solvent for the complex, a product with a specific surface area of 300 to 500 m² / g is recovered, the particle porosity of which is between 0.3 and 0.4 cm³ / g.

It is also known from US-A 4,499,194 to manufacture a support consisting of a complex of magnesium chloride and alcohol or phenol. According to this document, a magnesium chloride is reacted with an alcohol or a phenol in an inert organic solvent so as to form a complex, the assembly then being kept in suspension in an inert organic solvent at a temperature of 85 to 170 °. C so as to keep the complex in the molten state. From this hot suspension are precipitated by an organoaluminum compound or a silicon halide particles having a specific surface of 200 to 700 m² / g and a porosity of between 0.2 and 0.7 cm³ / g.

According to the process of the present invention it is possible to obtain a support in the form of solid particles consisting essentially of a complex of formula MgCl₂, x (n-BuOH) in which 0.1 ≦ x ≦ 2 and whose specific surface is from 1 to 20 m² / g and whose particle porosity is from 1 to 2 cm³ / g. The support is formed of solid particles, of average sizes from 10 to 100 μm, whose particle size distribution width, defined by the ratio D₉₀ / D₁₀ is less than or equal to 7, D₉₀ and D₁₀ being respectively the diameters below which one finds 90% and 10% by weight of the particles.

Usually in the support obtained the Cl / Mg mass ratio is 2.65 to 2.96 and the n-BuOH / Mg mass ratio is 0.4 to 6.

The process for manufacturing the support from MgCl₂ and n-butanol is characterized in that a solution of MgCl₂ in an excess of n-butanol emulsified in an emulsifying medium is treated with a precipitating agent of formula SiCl _x R _4-x in which 1 ≦ x ≦ 4. The complex formed, MgCl₂, x (n-BuOH) in which 0.1 ≦ x ≦ 2, is present in the emulsion and during precipitation at a temperature of at least plus 50 ° C.

In order to facilitate the dissolution of MgCl₂ in n-butanol, it is recommended to disperse MgCl₂ beforehand in a non-solvent organic liquid of MgCl₂ and chemically inert with respect to MgCl₂ and n-butanol, and to mix n- dispersion butanol. The dispersing liquid of MgCl2 must have a boiling point preferably less than or equal to 100 ° C; it is usually chosen from light hydrocarbons such as hexane.

In order to dissolve the MgCl₂ in n-butanol, the molar ratio n-butanol to MgCl₂ is generally at least 9 to facilitate the dissolution of the MgCl₂ in n-butanol and / or the handling of this solution to a temperature below 50 ° C. Although the higher molar ratio is not limiting, it is recommended, for economy and in order to limit the volumes of products to be handled, not to exceed an n-butanol molar ratio on MgCl₂ of 15. A clear and perfectly stable solution of MgCl₂ in n-butanol at a temperature not exceeding 50 ° C is obtained for a molar concentration of 10 n-butanol for 1 MgCl₂, therefore the best conditions for dissolving MgCl₂ in n-butanol are '' use, for the dissolution of MgCl₂, a molar ratio n-butanol on MgCl₂ from 9.5 to 10.5.

The MgCl₂ is dissolved, preferably with stirring, in n-butanol at a temperature of 20 to 110 ° C and preferably from 50 to 100 ° C. When the MgCl₂ as already indicated is previously dispersed in a dispersing liquid, the mixture, after addition of n-butanol, is maintained for a sufficient time and a sufficient temperature between 20 and 110 ° C and preferably from 50 to 100 ° C firstly to facilitate the dissolution of MgCl₂ in n-butanol and secondly to eliminate the liquid used for the dispersion. After this treatment, the solution obtained, once cooled, remains clear and stable at a temperature of at most 50 ° C.

The solution of MgCl₂ in n-butanol, after elimination of the possible dispersing liquid, is emulsified in an emulsifying medium which is a non-solvent organic liquid and inert with respect to the solution, in the presence of a tensio- non-ionic active ingredient at a temperature which can vary from room temperature to 50 ° C. The emulsifying organic liquid is preferably chosen from heavy hydrocarbons, such as paraffinic oils, with a viscosity at 20 ° C. of between 0.1 and 1 Pa.s. In the emulsion, the volume ratio of the emulsifying medium to the butanolic phase represented by the solution of MgCl₂ in n-butanol, is usually 1 to 5 and better still 2 to 3.

The well-known non-ionic surfactant has the function of facilitating maintenance in dispersed form in the emulsifying medium of droplets, in the specific case of butanolic solution of MgCl₂, formed by emulsion. This surfactant is preferably chosen from those with a hydrophyl-lipophyl balance (HLB) of between 0 and 9 and better still between 1 and 4. This HLB, defined by GRIFFIN in 1940, is characteristic of each surfactant. It sets an arbitrary scale of 0 to 20, admitting that lipophilic products have an HLB of 0 to 9 and that hydrophilic compounds have an HLB of 11 to 20. These surfactants can for example be fatty acid esters of sorbitan or glycerin such as sorbitan trioleate or glycerin mono and dioleate, or alternatively polyoxyethylenated fatty acid esters. The amount of surfactant added is of the order of 1 to 5% by weight, and better still 2 to 3%, of the whole dispersing medium and butanolic solution of MgCl₂.

The agitation must, as the skilled person knows, be sufficient to maintain the alcoholic phase in the form of droplets in the emulsifying medium. This being respected, the stirring conditions do not seem to be the most critical, in particular because of a better stability of the emulsion at process temperatures than at higher temperatures.

To this emulsion is added the precipitating agent which is a chlorinated derivative of silicon of formula SiCl _x R _4-x in which 1 ≦ x ≦ 4 and R is a saturated hydrocarbon radical containing from 1 to 4 carbon atoms. It is preferably added with stirring to the emulsion and slowly enough to control the formation of HCl and control the reaction. Although it can be added pure to the emulsion, the chlorinated derivative of silicon is usually added diluted in an inert solvent such as a hydrocarbon. The temperature of the emulsion is of course maintained in the range of the atmosphere at 50 ° C. during the precipitation of the MgCl₂, x (n-BuOH) complex, which facilitates the control of the morphology and physical characteristics of the final support.

The precipitated support can be conventionally recovered after filtration, washing with an inert organic liquid, such as a light hydrocarbon, and drying.

It may be recommended to subject the support to a second treatment with the chlorinated derivative of the preceding silicon. In this case, the support, as previously precipitated and isolated after optionally washing and even drying, is resuspended in an organic non-solvent liquid such as a hydrocarbon and treated a second time with the chlorinated derivative of silicon under analogous conditions. to those described for the first treatment.

Whether the treatment of the solution of MgCl₂ in n-butanol with the chlorinated silicon compound is carried out in one or two times the total amount of chlorinated silicon compound used is generally it that the molar ratio C1 of the chlorinated compound of silicon / n-butanol is from 1 to 8 and better still from 2 to 4.

A catalytic component can be obtained by combining the support according to the invention with a transition metal compound. Thus, for example, such a component can be obtained by impregnating the support with a titanium compound, preferably halogenated. This catalytic component associated with a cocatalyst chosen from the organometallic compounds of metals I to III of the periodic table and more particularly the aluminum compounds, serves as a catalyst for polymerization or copolymerization of linear or branched olefins such as ethylene, propylene, butene-1, hexene-1, octene-1, 4-methylpentene-1, butadiene-1-3.

At least one electron donor can be added, during its manufacture, to the catalytic component and / or to the cocatalyst. The electron donor can for example be chosen from Lewis acids, esters of oxygenated acids, ketones, aldehydes, ethers, amides and phosphorus compounds such as phosphines and phosphoramides, the preferred ones being alkyl esters of aromatic acids or mono or diethers of alkyl.

The catalyst obtained from a component manufactured from the support is suitable for all types of olefin polymerization: at high and low pressure, in suspension or in the gas phase.

The following examples illustrate the invention without, however, limiting it. The particle sizes, mean diameter D₅₀ and particle size distribution width defined by D₉₀ / D₁₀ are carried out using a MALVERN 1600 laser particle sizer. The specific surface is measured by isothermal physical adsorption of nitrogen at the temperature of nitrogen liquid, BET method, on a QUANTASORB device from the company QUANTACHROME. The pore volume is determined by adsorption of mercury under pressure with an ERBASCIENCE 1500 porosimeter.

EXAMPLE 1

450 ml of dry hexane then 150 g of anhydrous MgCl₂ are introduced successively into an 2 l reactor under inert atmosphere and with stirring. To this suspension is added 1440 ml of anhydrous n-butanol. The hexane is distilled by heating at 60 ° C for 1 hour under nitrogen sweep. During this stage the MgCl₂ dissolves. After returning to ambient temperature, the homogeneous solution has the following characteristics:% Mg = 3.02,% Cl = 8.9,% n-BuOH = 88, (% by weight), d _{20 ° C} = 0.95 g / cm³.

500 ml of a paraffinic oil with a viscosity at 20 ° C equal to 0.2 Pa.s, 16 g of sorbitan trioleate, are successively introduced into a 2 l reactor under an inert atmosphere, equipped with mechanical stirring. 200 ml of MgCl₂, 10 n-BuOH solution prepared above. After stirring for 30 minutes at 1000 rpm, a stable whitish emulsion is obtained with stirring.

225 ml of 5M SiCl₄ solution in hexane are slowly added over 45 min to this solution at 35 ° C. The mixture is then kept at 50 ° C for one hour. After cooling, the precipitated solid is filtered and washed three times with 300 ml of dry hexane, then dried under nitrogen.

The insulated support is granular and has the following characteristics: Cl / Mg = 2.7, n-BuOH / Mg = 1.55, surfaces = 2 m² / g, pore volume = 1.06 cm³ / g, average diameter, D50 = 43 µm, D90 / D10 = 5.2.

EXAMPLE 2

To the same quantity of emulsion, at a temperature of 35 ° C., prepared according to example 1, 130 ml of 5M SiCl₄ solution in hexane are added over 40 min. The mixture is then kept at 50 ° C for 1 hour. The precipitated solid is filtered and then resuspended in hexane. 130 ml of 5M SiCl₄ solution are then added and the mixture is again kept at 50 ° C. for 1 hour with gentle stirring. The solid is isolated as in Example 1.

The support has the following characteristics: Cl / Mg = 2.93, n-BuOH = 2.1, surface = 16.7 m² / g, pore volume = 1.79 cm³ / g. D₅₀ = 91 µm, D₉₀ / D₁₀ = 5.7.

EXAMPLE 3

In a reactor under nitrogen, 40 ml of dry heptane and 7.5 g of support from Example 1 are placed, then 28 ml of TiCl₄ is added with stirring. The mixture is brought to 90 ° C for 2 hours, filtered and washed with hexane at 50 ° C. The catalytic component obtained contains 6.1% by weight of Ti.

1.5 l of hexane, 5 mH of triisobutylaluminum and 13.5 mg of the above catalytic component are introduced into a 2.5 l reactor in order, at room temperature, under an inert atmosphere. Hydrogen is added to a partial pressure of 4.2 bar and made up with ethylene, adjusting the pressure to reach 11 bar absolute total pressure after heating to 80 ° C. This total pressure is kept constant for 3 hours by addition of ethylene. After 3 hours, we stops the injection of ethylene and the mixture is cooled to room temperature; the catalyst is deactivated by adding a 10% acid methanol solution. Is isolated after filtration and drying 550 g of polyethylene of melt index (Melt Index) under 2 kg at 190 ° C in 10 minutes MI₂ 0.98, or a productivity of 40,700 g PE / g catalyst.

EXAMPLE 4

In a reactor under nitrogen is added with stirring to 56 g of support of Example 2, 200 ml of TiCl₄ in 1000 ml of heptane. The mixture is brought to 90 ° C for 2 hours, filtered and washed with hexane at 50 ° C. The catalytic component obtained contains 8.4% by weight of Ti.

Polymerization of ethylene is carried out with 5 mg of the catalytic component, under the same conditions as in Example 3. The quantity of polymer produced is 610 g of polyethylene of MI₂ = 0.7, ie a productivity of 120,000 g PE / g catalyst.

EXAMPLE 5

In a reactor under nitrogen, place 5 g of the support of Example 2 in dry heptane. 2.5 mM of triethyl aluminum are added, and the mixture is brought to 50 ° C. for one hour. After washing with heptane, the solid thus obtained is taken up in 50 ml of a heptane solution of dioctylphthalate at 0.3 mole per liter for two hours at 90 ° C. After filtration and washing with heptane, the solid is treated twice with a 1 M / l solution of Ticl₄ in 1-2 dichloroethane for 2 hours at 80 ° C. After washing and drying, a solid catalytic component is obtained containing 4.7% by weight of titanium.

1.5 liters of liquid propylene, 4.5 mM of triethylaluminum and 0.45 mM of phenyltriethoxysilane are successively introduced into a stainless steel autoclave reactor, fitted with magnetic stirring and a jacket heating. 15 mg of catalytic component.

The temperature is brought to 70 ° C for 1 hour. 169.5 g of polypropylene are recovered, including 7.9 g of polymer soluble in boiling heptane. The catalytic activity is 240,000 g polymer / g Tih⁻¹. The polymer has good flowability and a narrow particle size distribution. The polymer has a melt index measured at 230 ° C under 2.16 kg, 3 g in 10 minutes.

Claims (12)

1. Catalyst support in the form of solid particles consisting essentially of an MgCl₂ and alcohol complex characterized in that the complex, of formula HgCl₂, x (n-BuOH) in which 0.1 ≦ x ≦ 2, has a specific surface of 1 to 20 ml / g, the porosity of the particles being 1 to 2 cm³ / g. 2. Support according to claim 1 characterized in that the particle size distribution width defined by the ratio D₉₀ / D₁₀ is such that D₉₀ / D₁₀ ≦ 7. 3. A method of manufacturing the catalyst support of claims 1 or 2 consisting in bringing MgCl₂ and n-butanol into contact, characterized in that a solution of MgCl₂ in an excess of n-butanol emulsified in an emulsifying medium is treated with a precipitating agent of formula SiCl _x R _4-x in which 1 ≦ x 4 and R being a saturated hydrocarbon radical containing from 1 to 4 carbon atoms, the complex formed being in the emulsion and during the precipitation at a temperature of at most 50 ° C. 4. Method according to claim 3 characterized in that in the solution the n-butanol / MgCl₂ molar ratio is at least 9. 5. Method according to one of claims 3 or 4 characterized in that the MgCl₂ is, prior to its dissolution in n-butanol, dispersed in an organic non-solvent liquid of MgCl₂ and chemically inert with respect to HgCl₂ and n-butanol. 6. Method according to claim 5 characterized in that the dispersing organic liquid has a boiling point less than or equal to 100 ° C. 7. Method according to one of claims 5 or 6 characterized in that the dispersing organic liquid is a hydrocarbon. 8. Method according to one of claims 5 to 7 characterized in that the organic dispersing liquid is eliminated from the solution of MgCl₂ in n-butanol prior to the emulsification of said solution. 9. Method according to one of claims 3 to 8 characterized in that the emulsifying medium is a hydrocarbon with viscosity at 20 ° C between 0.1 and 1 Pa.s. 10. Method according to one of claims 3 to 9 characterized in that the volume ratio of the emulsifying medium on the solution of MgCl₂ in n-butanol is from 1 to 5. 11. Method according to one of claims 3 to 10 characterized in that the total amount of chlorinated silicon compound used is such that the molar ratio C1 of the chlorinated silicon compound to n-butanol is from 1 to 8. 12. Catalytic component which can be used in the polymerization or copolymerization of olefins obtained by combination of a transition metal and optionally of an electron donor with the support of claims 1 to 3 or obtained according to the process of claims 4 to 11.